The BBC Trust is expected to ask the partners in Project Canvas, the joint venture between the BBC, ITV and BT to "bring catchup from the PC to the TV", for more in-depth information to better evaluate the service when it publishes the interim conclusions of its consultation into the proposal today.

It is unclear whether the demand will threaten the BBC Trust's original timetable for the consultation, which envisaged giving a final decision on whether the project could proceed by 24 July.

One senior executive with knowledge of the process said: "The BBC executive has been asked to give quite a lot more information to support the business plan for Canvas. There are four or five areas that have been highlighted by the BBC Trust that require more fleshing out."

The areas where the BBC Trust has demanded more in-depth information are thought to include technical standards, how the user interface will work and guidelines around the electronic programme guide, as well as more specific information about the makeup of the joint venture.

The media regulator also highlighted five areas of potential concern: technical standards; partnership arrangements with other companies; availability of Project Canvas to TV services other than Freeview or Freesat; navigation; and that quality standards for programmes made available via the online venture be "justifiable, non-discriminatory, transparent and proportionate".

Project Canvas's founding partners have been desperate to avoid the tag of "son of Kangaroo", pointing out that the venture aims to be an open technological platform for all content owners to bring catchup and on-demand TV to free-to-air digital TV services such as Freeview and Freesat.

However, the BBC Trust has, somewhat controversially, decided that Project Canvas will not require a full public value test, which would entail Ofcom conducting a market impact assessment of it on how it would affect commercial rivals.

The trust has concluded that the venture is only subject to its own review as it is not a new BBC service but a joint venture operating platform.

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